Large-scale Internet application systems, especially those using wireless connections, have large numbers of users. For example, WeChat, a social communication platform operated by Tencent Co. Ltd., provides instant communication and other social functions to mobile terminal (e.g., smart phone) users all over the world. Because the users of an Internet application are generally distributed in multiple regions all over the country, when they connect to a server of the network of the Internet application through a wireless connection, system delays often occur. To solve this problem, one or more service nodes are generally deployed in each region and dedicated to meeting the service needs of the users in that region. However, allocating service nodes to a terminal user merely based on his/her geographical location does not guarantee a reliable connection without delay. This is because the quality of Internet connection varies over time. A node that is geographically close to a terminal user may have a good Internet connection when it is allocated to the terminal user, but the connection may become worse after the terminal user is connected. Consequently, the network quality achieved between the terminal user and the allocated service nodes cannot be guaranteed.